The objectives will be (1) to determine whether established cell lines (LT cells) derived by cocultivation of Lucke tumor cells with nontransformed amphibian cells carry latent Lucke herpesvirus (LHV) genomes, and (2) to activate and characterize latent viruses which may be present in the established cell lines. Detection of LHV genomes in LT cells will be done by molecular hybridization and immunologic techniques (immunofluorescence and immunodiffusion). To activate latent viruses in LT cells the cells will be treated with UV-irradiation, X-rays, chemical inducers, or exogenously added helper viruses. The last objective involves a study of the formation, composition, and enzymatic activities of PCDV replicating DNA complexes isolated from infected baby hamster kidney or LT cells. Replicating DNA complexes will be isolated by rate zonal centrifugation and analyzed by analytical disc gel electrophoresis for protein composition and assayed in vitro for enzymatic activities (e.g. polymerases, protein kinase, nucleases).